1. Field of the Invention
The present invention relates to an improvement in a camera system constituted by an auxiliary device such as a lens device which comprises a plurality of actuators, i.e., at least two motors (e.g., a driving motor for a focusing lens and a driving motor for a focal length adjusting lens), and a camera (main body) to which the auxiliary device such as the lens device is attached.
2. Related Background Art
In recent years, in camera systems which allow to interchange lenses, an auto-focus camera having an automatic focusing function of a photo-taking lens, and a so-called power-zoom camera or auto-zoom camera which drives a variable power optical system of a photo-taking lens by an actuator such as a motor are known. In order to further improve the function of an interchangeable lens, lenses having an image blur prevention function have been developed.
Along with such improvement of the functions of lenses, the number of actuators in a lens tends to increase, and electrical power required for such an improved-function lens inevitably increases.
However, in a conventional camera system which allows to interchange lenses, an electrical power level to be supplied from a power supply battery incorporated in a camera (main body) to a lens, and a power supply condition for determining the operation inhibition level of the remaining capacity of a battery are uniquely determined, and it is inconvenient to use lenses having different required electrical power levels while interchanging such lenses.
For example, when the electrical power level to be supplied to a lens is determined to be low irrespective of an increase in the number of actuators in a lens, the low electrical power level disturbs development of an improved-function lens including a larger number of actuators as an interchangeable lens, and the actuators in the lens cannot often be driven at a sufficient speed. Conversely, when the electrical power level is determined to be high, a wasteful electrical power loss increases when a lens which requires only a low electrical power level is attached, and the operation of the camera system is inhibited at a remaining capacity level of a battery which is determined in consideration of the high electrical power level, before the battery is fully used up, resulting in inconvenience.